JPH0532724A - High reflective-index synthetic resin optical material - Google Patents

Abstract

PURPOSE:To provide the subject material composed of a copolymer produced by addition polymerization of a specified ratio of a specified compound and divinyl benzene and having a refractive index and an Abbe's number respectively higher than a prescribed value, showing a high refractive index and a low dispersibility, excellent in transparency and chemical resistance and useful as lens, etc. CONSTITUTION:An objective material composed of a copolymer produced by addition polymerization of a mixture containing (A) a dithiol compound [e.g. 1,4-bis(2-mercaptoethylenethio)xylylene] shown by the formula (n is 1-3) and (B) divinyl benzene in 0.25-3.5 weight ratio of the component (A) based on the component (B) and showing >=1.63 reflective index and >=27 Abbe's number.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin optical material having a high refractive index, and particularly to a high refractive index synthetic resin optical material having a low dispersibility.

[0002]

2. Description of the Related Art Conventionally, various inorganic glass lenses have been used in optical instruments, but recently, synthetic resin lenses are light in weight, workability, stability, dyeability, mass productivity, and cost. Due to its potential for reduction, it is beginning to be widely used with inorganic glass lenses.

Among the various physical properties required for an optical lens, high refractive index and low dispersion are extremely important. With a lens made of an optical material having a high refractive index, for example, a lens system that occupies an important position in an optical device such as a microscope, a camera, a telescope or a spectacle lens can be made compact, and a weight reduction and a spherical surface can be achieved. It is possible to suppress the aberration due to the above. On the other hand, the low dispersion of the optical material is extremely important in that the chromatic aberration of the lens is reduced.

However, even in synthetic resin lens materials,
Like inorganic glass lens materials, high refractive index materials tend to have high dispersion, while low refractive index materials tend to have low dispersion. For example, the most widely used synthetic resin lens material for spectacles at present is a diethylene glycol bisallyl carbonate resin called "CR-39". Although this resin has a high Abbe number of 60 (that is, a low dispersion), its refractive index (a value at a temperature of 20 ° C., the same applies below) is extremely low at 1.50. Also, polymethylmethacrylate used in some fields as a lens material has an Abbe number of 60.
However, the refractive index is as low as 1.49.

On the other hand, polystyrene, which is said to have a relatively high refractive index and low dispersion, has a refractive index of 1.59 and an Abbe number of 30.4. Similarly, polycarbonate has a refractive index of 1.59 and an Abbe number. The number is 29.5. However, these synthetic resins are not satisfactory in other physical properties as a lens material. For example, polystyrene has a low surface hardness and lacks solvent resistance, while polycarbonate has a low surface hardness and lacks impact resistance. Furthermore, polynaphthylmethacrylate having a refractive index of 1.64 and polyvinylnaphthalene having a refractive index of 1.68 have Abbe numbers of 24 and 20, respectively, which are considerably low, and neither is a good optical material.

[0006]

As described above, synthetic resin optical materials having excellent optical characteristics such as a high refractive index and low dispersion and good physical characteristics are known in the past. Absent. The present invention has been made based on these circumstances, and an object thereof is to provide a high refractive index composite having excellent optical characteristics such as a high refractive index and low dispersion, and good physical characteristics. It is to provide a resin optical material.

[0007]

The high refractive index synthetic resin optical material of the present invention comprises an A component composed of a dithiol compound represented by the following chemical formula 2 and a B component composed of divinylbenzene, and A copolymer having a refractive index of 1.63 or more and an Abbe number of 27 or more, which is obtained by addition-polymerizing a mixture containing the components in a weight ratio of 0.25 to 3.5. Is characterized by.

[0008]

[Chemical 2]

The present invention will be described in detail below. The high refractive index synthetic resin optical material of the present invention comprises a specific A component and B
And an addition copolymer obtained from a comonomer component. The main component of this copolymer is formed by the dithiol compound of the component A shown in Chemical formula 2 above. The magnitude of the value of n in the chemical formula 2 is importantly related to the optical properties of the obtained copolymer. That is, this n
When the value of is increased, the dithiol compound tends to have a reduced compatibility with the component B divinylbenzene, and in particular, the dithiol compound having n of 4 or more has an insufficient compatibility with the component B. The resulting copolymer has low transparency. Therefore, in the present invention, in the chemical formula 2, a dithiol compound having a value of n of 1 to 3 is used as the A component.

In the chemical formula 2 showing the dithiol compound as the component A, when a dithiol compound in which two methylene groups in the aromatic ring have different substitution positions is used, the optical properties of the resulting copolymer are slightly different. For example, a copolymer obtained from a dithiol compound having a substitution position at the para position has a slightly higher refractive index than a copolymer obtained from a dithiol compound having another substitution position. On the other hand, the dithiol compound in which the substitution position of the methylene group is in the meta position or the ortho position is
Since the compatibility with the component divinylbenzene is high, it is possible to obtain an optical material having extremely high transparency. Therefore, dithiol compounds at various substitution positions can be used as the A component depending on the purpose of use of the optical material.

Specific examples of the dithiol compound represented by Chemical formula 2 include the following, but the component A used in the present invention is not limited to these. (1) 1,4-bis (2-mercaptoethylenethio) xylylene (2) 1,3-bis (2-mercaptoethylenethio) xylylene (3) 1,4-bis (2-mercaptothioethoxyethylenethio) xylylene (4) 1,3-bis (2-mercaptothioethoxyethylenethio) xylylene (5) 1,2-bis (2-mercaptothioethoxyethylenethio) xylylene (6) 1,4-bis (2-mercaptodithioethoxy) Ethylenethio) xylylene (7) 1,3-bis (2-mercaptodithioethoxyethylenethio) xylylene The structures of the above dithiol compounds are as shown in Chemical Formula 3 below.

[0012]

[Chemical 3]

The component A as described above does not polymerize alone, but in the present invention, a copolymer obtained by addition-polymerizing divinylbenzene as the component B with the component A is used as an optical material. Divinylbenzene is a crosslinkable monomer having two vinyl groups capable of addition polymerization or copolymerization in its molecule. The divinylbenzene used here must have high purity. Commercially available divinylbenzene usually contains a large amount of impurities and thus does not smoothly undergo addition polymerization, so that a high molecular weight polymer cannot be efficiently obtained. Specifically, the purity is 70% or more, especially 75%
It is preferable to use the above divinylbenzene. When divinylbenzene having a purity of less than 70% is used, the intended polymerization reaction with the component A is hindered and the molecular weight does not become sufficiently high. Therefore, the obtained copolymer does not have high hardness, It is difficult to obtain a copolymer having high solvent resistance, and since the copolymer contains a low molecular weight component in a large proportion, it has a low mechanical strength. It may be damaged during processing.

In the above-mentioned A component and B component, the value of the weight ratio α of the A component (A component / B component) to the B component is 0.25.
Used in ratios that range from 3.5. The value of α is preferably 0.4 to 2.5, and more preferably 0.55.
It is preferably 2.0. When the value of α is less than 0.25, the proportion of the component A is small, and therefore the target copolymer having a high refractive index and low dispersion, specifically, a refractive index of 1.63 or more and It is difficult to obtain a copolymer having the Abbe number of 27 or more. On the other hand, when the value of α exceeds 3.5, the proportion of the B component becomes small, so that the obtained copolymer has a low degree of addition polymerization and a low degree of crosslinking, and as a result, is required as an optical material. It is not possible to obtain a copolymer having good physical properties such as high hardness.

The addition polymerization reaction of the A component and the B component proceeds with a usual radical polymerization initiator. Therefore, the polymerization method and reaction conditions for this addition polymerization reaction may be the same as in the case of a normal radical polymerization reaction. However, in the divinylbenzene used as the B component, a part of it is polymerized by itself to cause a crosslinking reaction, and as a result, it is practically impossible to perform a treatment involving dissolution or melting of the resulting copolymer. Therefore, it is generally preferable to use the cast polymerization method that directly obtains the desired shape of the optical material.

The cast polymerization method is a well-known technique and can be applied to the present invention as it is. As the casting polymerization container, a plate, a lens, a cylinder, a prism, a cone, a sphere, a mold or a mold designed according to the purpose or application, and other containers are used. The material can be selected from inorganic glass, plastic, metal, and any other material depending on the purpose. The actual polymerization reaction can be carried out by charging a mixture of the components A and B and a polymerization initiator into a casting polymerization container and heating the mixture. It is also possible to carry out the polymerization by completing the polymerization by allowing the monomer mixture to react to a certain extent and adding the prepolymer or syrup having an increased viscosity into the casting polymerization vessel. The required monomer components and the polymerization initiator may be mixed at once at once, or may be mixed stepwise. The monomer mixture contains an antistatic agent, a colorant, a filler, a UV absorber, a heat stabilizer, an antioxidant, and other auxiliary materials depending on the intended use of the resulting copolymer. be able to.

[0017]

The copolymer according to the optical material of the present invention contains a specific dithiol compound as its monomer component,
It has a high refractive index and low dispersion, specifically, a refractive index of 1.63 or more and an Abbe number of 27 or more. The optical material of the present invention is characterized in that the copolymer is composed of the specific monomer component as described above. Therefore, in order to obtain an actual optical material by using the copolymer, means conventionally used can be applied. That is, it is possible to use a means for directly obtaining an optical material having a specific shape by a cast polymerization method, a means for shaving an optical material having a desired shape from a plate or a lump, and the like. This optical material further includes surface polishing treatment, antistatic treatment, and
Other post-treatments can be performed to obtain an optical material having desired performance. Further, in order to increase the surface hardness of the optical material, it is possible to coat the surface with an appropriate inorganic material or an organic coating agent by dipping or the like.

[0018]

EXAMPLES Examples of the present invention will be described below.
The present invention is not limited to these.

Example 1 40 parts by weight of sufficiently purified 98% pure 1,3-bis (2-mercaptoethylenethio) xylylene and a purity of 81%
% Divinylbenzene (60 parts by weight), and 1.2 parts by weight of tert-butyl peroxyneodecanoate, which is a polymerization initiator, was added thereto and thoroughly mixed. Here, the value of the weight ratio α of the A component to the B component is 0.81. This mixed solution is poured into a glass lens mold and heated at 50 ° C. for 10 hours, 60 ° C. for 8 hours, 80 ° C. for 3 hours, and 100 ° C. for 2 hours at different temperatures to carry out polymerization. Upon completion, this produced a -2.00 diopter colorless transparent lens.

This lens had a refractive index of 1.632 and an Abbe number of 28.8, and had a sufficiently high refractive index and a sufficiently low dispersion. Further, this lens was completely insoluble in acetone and benzene and had a high resistance to organic solvents. Furthermore, the surface hardness (J
According to pencil hardness according to IS K5400. The same applies below. ) Is 3H, the penetration temperature showing heat resistance (JIS K
The temperature at which the penetration measured according to 7206 is 0.4 mm. The same applies below. ) Was 110 ° C., which were all excellent. From these facts, the copolymer according to this lens has excellent optical characteristics, and also has a sufficiently high degree of polymerization and high mechanical strength and good physical characteristics. It's clear that it's very balanced.

Example 2 50 parts by weight of sufficiently purified 98% pure 1,4-bis (2-mercaptoethylenethio) xylylene and a purity of 81%
Polymerization was carried out in the same manner as in Example 1 using 50% by weight of divinylbenzene (%) to produce a +2.25 diopter colorless transparent lens. Here, the value of the weight ratio α of the A component to the B component is 1.21. This lens had a refractive index of 1.642 and an Abbe number of 29.5 and had a sufficiently high refractive index and a sufficiently low dispersion. This lens was completely insoluble in acetone and benzene, had a surface hardness of 3H and a penetration temperature of 95 ° C.

Comparative Example 1 1,3-Bis (2-) having a purity of 98% used in Example 1
Using 15 parts by weight of mercaptoethylenethio) xylylene and 85 parts by weight of divinylbenzene having a purity of 81%, polymerization was carried out in the same manner as in Example 1 to produce a lens. Here, the value of the weight ratio α of the A component to the B component is 0.21. This lens had an Abbe number of 28, but had a low refractive index of 1.619. This is because the proportion of the A component is small.

Reference Example 1 Polymerization was carried out in the same manner as in Example 1 except that 40 parts by weight of 1,3-bis (2-mercaptoethylenethio) xylylene having a purity of 98% and 60 parts by weight of divinylbenzene having a purity of 55% were used. Then, a lens was manufactured. Here, the value of the weight ratio α of the A component to the B component is 1.19. Although this lens was transparent, it was flexible and easily deformed by the force of a finger at room temperature, and its heat resistance was considerably low, and it was unusable. Further, in the measurement of the refractive index by Abbe's refractometer, it was easily dissolved in the contact liquid used, and it was practically impossible to measure the refractive index. From this, it is understood that when the purity of divinylbenzene actually used is low, the resulting copolymer is inferior in heat resistance and solvent resistance.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that 78 parts by weight of 1,3-bis (2-mercaptoethylenethio) xylylene having a purity of 98% and 22 parts by weight of divinylbenzene having a purity of 81% were used. I went. However, the obtained molded product was in a gel form and was not completely solidified, and could not be put to practical use as a lens at all. Here, the value of the weight ratio α of the A component to the B component is 4.29. From this example, it is understood that when the proportion of the dithiol compound is too large and the proportion of the divinylbenzene is small, a copolymer having a high degree of polymerization cannot be obtained and a practical lens cannot be manufactured.

Example 3 35 parts by weight of sufficiently purified 1,3-bis (2-mercaptothioethoxyethylenethio) xylylene having a purity of 98% and 65 parts by weight of divinylbenzene having a purity of 81% were sufficiently mixed. Polymerization was carried out in the same manner as in Example 1 and +2.0.
0 diopter colorless transparent lenses were produced. here,
The value of the weight ratio α of the A component to the B component is 0.65. This lens had a refractive index of 1.631 and an Abbe number of 29.1 and had a sufficiently high refractive index and a sufficiently low dispersion. In addition, this lens is completely insoluble in acetone and benzene, and has a surface hardness of 3H,
The penetration temperature was 126 ° C.

Example 4 Example 1 using 33 parts by weight of fully purified 99% pure 1,3-bis (2-mercaptothioethoxyethylenethio) xylylene and 67 parts by weight divinylbenzene 81% purity. Polymerization was carried out in the same manner as above to produce a colorless and transparent lens of -4.50 diopter. Here, the value of the weight ratio α of the A component to the B component is 0.60. This lens has a refractive index of 1.644 and an Abbe number of 31.0.
And had a sufficiently high refractive index and a sufficiently low dispersion. This lens was completely insoluble in acetone and benzene, had a surface hardness of 3H and a penetration temperature of 130 ° C.

Example 5 68 parts by weight of fully purified 98% pure 1,3-bis (2-mercaptoethylenethio) xylylene and a purity of 81%
% And 32 parts by weight of divinylbenzene were polymerized in the same manner as in Example 1 to produce a colorless and transparent lens.
Here, the value of the weight ratio α of the A component to the B component is 2.5.
7 This lens had a refractive index of 1.631 and an Abbe number of 34.3, and had a sufficiently excellent balance between the refractive index and the Abbe number. Also, this lens
It was completely insoluble in acetone and benzene, had a surface hardness of 2H and a penetration temperature of 70 ° C.

[0028]

As described above, the optical material according to the present invention is
The copolymer has a high refractive index of 1.63 or more, an Abbe number of 27 or more, which is sufficiently low dispersion, and has high colorless transparency, and has optical characteristics particularly suitable as a lens. It also has excellent physical properties such as solvent resistance, heat resistance, and physical properties such as surface hardness.

Claims (1)

Claim: What is claimed is: 1. A component composed of a dithiol compound represented by the following chemical formula 1 and a B component composed of divinylbenzene, wherein the ratio of the A component to the B component is 0.25 to 3.5. A high-refractive-index synthetic resin optical, characterized by comprising a copolymer having a refractive index of 1.63 or more and an Abbe number of 27 or more, which is obtained by addition-polymerizing a mixture containing them in a weight ratio of material. [Chemical 1]